Amplifier for phonographs and the like



E. PHIPPS.

AMPLIFIER FOR PHONOGRAPHS AND THE LIKE.

APPLICATION FILED FEB- 25. 1920.

Patented Julie '14, 1921.

p WP UNITED STATES- EDWARD PHIYPS, OF SAN FRANCISCO, CALIFORNIA.

AMPLIFIER FOR PHOLIOGRAPHS AND THE LIKE.

Specification of Letters Patent.

Patented June 14, 1921.

Application filed February 25, 1920. Serial No. 361,185.

To all whom it may concern:

Be it known that I, EDWARD PHIPPS, a citizen of the United States,residing at San Francisco, in the county of San Francisco and State ofCalifornia, have inventednew and useful Improvements in Amplifiers forPhonographs and the like, of which the following is a specification.

Thisinvention resides in the provision of a phonograph tone amplifierwhich will enrich the quality of, and better articulate, the tones so asto render a more natural and harmonious reproduction of the originaltones. An object of the invention is to provide an amplifier of thecharacter described which is constructed in a novel, simple, andrelatively inexpensive manner and may be easily and quickly made andassembled.

The invention possesses other advantages and features, some of which,with the foregoing, will be set forth at length in the followingdescription wherein I shall outline in full that form of the inventionwhich I have selected for illustration in the drawings accompanying andforming a part of the resent specification. In said drawings, I aveshown one form of the construction of my invention but it is to beunderstood that I do not limit myself to such form, since the inventionas expressed in the claims may be embodied in a plurality of forms.

Referring to the drawings:

Figure 1 is a front elevation of the sound amplifier of my invention.

Flg. 2 is a longitudinal sectional view I taken on the line 2-2 of Fig.1.

Fig. 3 is a sectional View taken on the line 3-3 of Fig. 2, showing theamplifier proper in top plan.

In carrying out my invention, I construct a sound amplifying chamber ofrelatively thin highly resonant wood somewhat after the manner usuallyfollowed in the art, but instead of having the flare of the chamberextend clear to the outer end thereof, I converge the walls of thechamber at the outer end and restrict the sound outlet opening of thechamber somewhat. This, I have found, causes better articulation of thetones. It is known in the art that very thin resonant wood producesbetter tone results in sound amplifiers but unless the thin wood is insome manner'damped in its vibration tendency, too much vibrationresults, and spoils the tone. Sound amplifying chambers have heretoforebeen formed of wood of such thickness that the objections above notedwere eliminated and consequently a very thin wood has not beensuccessfully employed. I have found that by bending very thm sheets ofwood into curves, preferably of substantially ogee form, and form- 1ng achamber of said sheets, I place the wood under a certain tension whichprevents too great a vibration but produces better resonating qualitiesand I thus may use exceptlonally thin wood and obtain the advantagesthereof without the objections heretofore encountered in the use of verythin wood.

In one form ofthe invention, as shown in the drawing, I employ a throat1 preferably formed of similar wooden halves 2 joined in any suitablemanner and havin a circular opening 3 therethrough. This t roat standsvertically, the upper end being suitably connected with the tone arm,not shown, whereas the lower end is curved outwardly, as at 4:, andprovided with a rectilinear opening 5. This opening 5 gradually mergesinto the clrcular openlng 3. The amplifier 6 is mounted in the openin 5in a recess 7 in said opening wherebytIie inner surfaces of theamplifier and opening 5 are flush with one another. 1

The amplifier comprises upper and lower portions or walls 8 and 9, andside walls 10 and 11. These walls are each made of one piece of verythin resonant wood veneer. The top and bottom walls 8 and 9 are curved nsubstant ally ogee form and from their inner ends, their longitudinaledges extend parallel, as at 12, a short distance, then dlvergeoutwardly in similarly rounding curves, as at 13, to points 14 neartheir outer end and from these points these and the outer ends of thesewalls converge, as at 15, to the ends of the walls. Thus the side edgesof the top and bottom walls de'fine identical curves of substantiallyogee outline. The degree of curvature of the bottom wall 9 is the sameas that of the top wall to the point 14 and from this point is less thanthe degree of curvature of the top wall from a corresponding point tothe outer end of said walls. This arrangement provides more sound areaat the outer end of the box above a line drawn horizontally through thecenter pomt at the inner end of the box and produces certain acousticalresults which tend to improve the quality of the tones.

side edges .1 said walls;

.the+oge e curvature of the vrespective to and bottom walls 8 and 9, thelower longitudinal edges of these side walls-being of less curyaturefromthe point 14 to their outer ends than the upper longitudinal edges of II: may secure-.- these ,walls together by providing: grooves 17 on theopposed faces of the. sidewalls-'10 and 11, and mortisin the side'edgesof thetop. and bottom wal s in :said grooves as shown in ,Fig. 1of the drawlt willfbe seen'that the sound amplifier or chamber of myinvention comprises a reduced neck portion 18 at .the inner end and.anenlarged-portion 19 at the outer end formed by'the .ogee curvedwooden sheets joined to ether in box-like form. B converging t e outerends of the walls, form a restrlcted sound outlet for a large soundchamber and cause the tones to be fully formed in the chamber beforeissuing therefrom and'to issue in concentrated form, so that in all thetones are better articulated thanin amplifiers which flare instead ofconverging at their tone outlet ends. This,- with the degree of tensionproduced in the highly resonant thin. wood of the amplifier by thepeculiar-curving of the walls thereof and also with the peculiar shapeof the chamber, goes to make up a sound amplifier which will producetrue, distinct, and fully har-' monious tones marked with thepresenceofi quality and with the absence of harshness and indistinctnessof tone.

By having the ends of the walls turned inwardly or converged, I placethe wood under such tension that a better acoustical result follows forreasons hereinbefore noted.

Since it is a known fact that a tensioned sheet of wood or other fibrousmaterial has better resonating qualities than an untensioned sheet, itis seen that it is one of the most important features of this inventionto provide for tensioning the entire area of the am lifier. Preferablthis is accompllshed y securing toget er a plurality of walls, each ofwhich comprises a single continuous sheet of wood Veneer and is formedlongitudinally as an ogee curve, whereby said walls are maintained understress.

I- claim 1.'A phonograph amplifier comprising a plurality of walls, eachof which comprises a single continuous sheet of wood veneer formedlongitudinally as an ogee curve, whereby said walls are maintained understress.

2. A phonograph amplifier comprising a plurality of walls of relativelythin resonatmg material, each of said walls being formed as an ogeecurve whereby said-walls are maintained under stress.

' EDWARD PHIPPS.

